1. Field of the Invention
This invention relates to a burn-in test device, more particularly to an apparatus for carrying out burn-in test of a device under test including semiconductors and light emitting diode (LED) arrays.
2. Description of Related Arts
Electronic device such as semiconductors and light emitting diodes (LED) are often subjected to burn-in test to determine stress strength, operating lifespan and defectiveness of said electronic device. The burn-in test machine simulates various environmental conditions during the test. The device under test that presents in array form is easier to be handled than in singular unit. In array form, the quantity of the device under test is large ranging from a few hundreds to a few thousands.
The contemporary bright LEDs and high speed semiconductors are often small in size and driven by high electrical power. When combining these devices in large amount in array form, substantially high electrical power consumption (from a few hundred watts to a few kilowatts or more) is required in order to provide constant electrical current to said device during the burn-in test. This has created a huge challenge in thermal management involving cooling down the temperature of the device under test and regulating predefined sets of environmental conditions during the burn-in test.
Various attempts in configuring the thermal management system for burn-in test have been disclosed in the prior arts. The U.S. Pat. No. 5,579,826 disclosed a thermal control system to be utilized in a burn-in system for semiconductors, which generally comprises a thermocouple, liquid reservoir, liquid, pump, spray array and a controller for controlling flow of the thermal and cooling elements to the spray array. Said liquid will be sprayed on the semiconductor to regulate the temperature and reused.
Another example of thermal management system for burn-in of semiconductors has been disclosed in U.S. Pat. No. 6,857,283 B2. Said system is a closed loop spray cooling system, which has two spray portions and one of them is extendable to reduce distance between the test object surface and the thermal management system to cool the heated temperature.
U.S. Publication No. 2005/0067146 A1 presents an apparatus functioning as a cooling system for burn-in of a semiconductor device. The cooling system uses evaporator containing a capillary wick to draw a coolant liquid from a pool which in turn cools the semiconductor. A condenser arranged in fluid communication with the evaporator.
A thermal control unit which dissipate heat with the use of a heat pipe is disclosed in U.S. Pat. No. 8,274,300 B2. Another known prior art which may be pertinent is Shimada T. et al., “Developing temperature control technology: Utilizing a mist-cooling system for devices that generate high temperature”, Journal of Espec Technology Report No. 19. A mist cooling system is utilised in said journal to cool down the temperature of the electronic device.
There are some drawbacks and limitations of the apparatuses disclosed in the prior arts as their construction and operation unable to provide an effective thermal and cold temperature regulation during the burn-in test as above-mentioned. Therefore, there is a need to provide an improved apparatus for burn-in test, which could overcome the aforementioned shortcomings.